As always there are to many options. If you have a separate genset a
120VAC holding plate might make sense. 120VAC refrigeration on an
inverter makes no sense at all to me. 12VDC or engine driven holding
plates means running the engine at least once a day and often twice.
THere are several 12VDC alternator geenset/watermakers out there but I
don't recall one with a compressor. I suppose you could add one in
place of or in addition to the watermaker pump.

This is just my theory but it seems to have worked out on the boats I
have either chartered or delivered. If you are shopping regularly and
loading the box with warm stuff expecting the box to chill it down the
evaporators work better because they can pull out a lot of BTUs fairly
quickly if allowed to run flat out. Holding plates will pull out BTUs
at a more regular rate. OTOH, if the box is stocked for a long passage
and you are not constantly adding new stuff the holding plate is more
efficient once everything is chilled down.

I am going with a pair of evaporator systems. One for the refrigerator
and one for the freezer. Here is how I arrived at this choice. First I
have plenty of power. 250 amp alternator and two 120 watt solar panels
charging 780 amp hours of L16HC batteries. Second, I want a copious
amount of ice for my sun downers. Third RUTU is designed for the
occasional run to Bermuda and Western Caribbean but primarily coastal
sailing and a lot of island hopping but definitely not for the South
Pacific. I expect weekly if not daily restocking. I expect my crew to
consist mostly of under 30 males which means a constant flow of beer and
soft drinks passing through the fridge. Forth Rutu will spend several
months a year in a slip 4 hours away. I want to keep the fridge stocked
and ready when I get to the boat on Friday afternoon. And finally I
wanted a system that was easy to install because I will be doing it
myself.

Everyone should develop their own criteria but those are mine.

Skip Gundlach wrote:

Hi, Glenn, and thanks for the response.

My expected pattern will be on the hook for extended periods of time,
particularly in the high season, when I/we expect to be working, perhaps 7
days a week, long hours. Since part of the reason for going offshore for
the rest of my life is peace and quiet, running engines or generators isn't
very appealing, and so I expect to have substantial solar and wind
generation to minimize that. Of course, once under way, there will be
enough instances of running the engine, I expect, that it won't be of issue
very often.

So, I'm anticipating doing something using 12V, if for no other reason than
greater efficiency than having to turn it into 120V, when I'm not running
some IC power source. I'm currently open on the subject of (IC[diesel - I
don't think I'd consider gas]) generators, but nearly certainly would not
buy one if it didn't come with the boat we buy. But, if we had one, likely
I'd like a combo ability (12V/120V), perhaps even with a tie-in to an
engine-driven compressor if it's cold plates we use.

Have you done any calculations on the load required to run cold plates
(daily amp hours) vs evaporators for the ability to keep a given volume to a
given temperature? One of the boat types we've considered has an example of
a refit set of evaporators, so it has me thinking... (They wrapped it
around the previous freezer section, entirely, at the top, and had a box/lid
topmounted in the previous reefer space, each having their own knob
temperature adjusters. I don't recall the brand, but there were two
compressors in the engine room, backed up against the reefer/frig space.)

Thanks.

L8R

Skip (and Lydia)

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

This past July I replaced my 120V Grunert holding plate system with a 12
V system that I built from parts from RParts.com. My major reasons for
doing this were (not necessarily in any order):

1) I could generate 12V from a large number of sources:

a) Solar panels
b) A KISS wind generator
c) The Heart Inverter/Charger that runs off the generator or shore AC
d) The alternator

2) My Fischer Panda generator was completely unreliable. As a result I
was trying to move away from relying on 120V. The Fischer Panda was
replaced by a NextGen generator which I hope will be much more reliable.

3) I am virtually never at a dock. I spend 6-8 months a year cruising
and am headed to the South Pacific this year. When I am at dock I can
use the shore power through the charger.

4) My holding plates do a great job of of maintaining temperature in the
compartments. I personally know of very few cruisers who use evaporator
style systems, other than those who have very small systems. Then
again, I know some cruisers who don't have *any* refrigeration, but I
can't imagine living that way!

5) After researching my various options I decided upon a 1/2 HP Glacier
Bay motor direct coupled to a Bitzer IIY compressor. For all intents
and purposes, this is a Glacier Bay system except that I use Grunert
holding plates rather than Glacier Bay holding plates. The Glacier Bay
holding plates are more efficient due to their use of spider capilary
tubes, but I couldn't justify the cost relative to the performance gain.
I switched from R404A to R134A.

6) I wanted to build the entire system myself as I need to maintain the
system while out cruising. Before doing this refrigeration was a bit of
a mystery. Now I've got a good handle on it as well as having the tools
(pumps, sniffers, etc) necessary to maintain it.

7) The system is running just great. It runs for about 2 to 2.5 hours
per day in daily day time temps in the low 90s and night time temps in
to low 80s. It cycles on demand. I redid the circuitry so that only
one zone runs at a time. This is MUCH more efficient than allowing both
zones to run simultaneously.

I don't know if this helps at all, but it's just one more data point.

-- Geoff

P.S. If you want to see pictures of the components and the assembled
system, you can find them at

http://www.geoffschultz.org/2003_Sai...ork/index.html

-- Geoff